[okl4-developer] L4 root task info

[Geoffrey Lee]

On Mon, Nov 10, 2008 at 03:02:09PM -0800, uf65ca wrote:
> 
> 
> *****************************
> 
> Thanks for your reply, 
> 
> regarding the scheduling of roottask, it's different from what I got from
> this link:
> http://i30www.ira.uka.de/~l4hq/cgi-bin/research/pistachio-faqwiz/faqw.py?req=all#6.4
> 
> "...sigma0, sigma1, and the roottask. Since the scheduler of all three
> threads is unkown, invoking the ThreadControl system call can fail. Thus,
> none of the mentioned scheduling state of these threads can be reliably
> set."

Please do not refer to this for information on OKL4.  OKL4 was 
derived from the Pistachio kernel, but it is quite different.  
Our wiki contains documentation relevant to OKL4.

> 
> 
> also I don't think you can claim "L4 strictly obeys the priority for threads
> with different priority
> numbers" as long as "direct switch" mechanism is used in sync-IPC.

Again, OKL4 is different to how Pistachio behaves.  The current
OKL4 kernel will always obey the priorities, even during an 
IPC.  The only instance in the current kernel where this is 
not true is if a higher priority thread voluntarily yields the
remaining timeslice of the processor to a specified lower priority 
thread.

> 
> Can I set  the priority of the roottask at *build* time, via a config file,
> to a rather low level (almost lowest level in the system)?  no, I'm not
> talking about lowering roottask priority @ runtime thru syscall?   
> is there any hidden assumption that roottask has the highest priority when
> created?
> 

It is currently not possible to set the priority of the initial root
thread at build time, it needs to be changed via a system call.

> Thanks

	-gl

> 
> 
> 
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